piclist 2008\07\17\103343a >
Thread: SDHC Cards, was Re: Digital Sound
www.piclist.com/techref/io/audio.htm?key=sound
face picon face BY : M. Adam Davis email (remove spam text)



On 7/17/08, Alan B. Pearce <RemoveMEA.B.PearcespamspamTakeThisOuTrl.ac.uk> wrote:
> Dunno 'bout that, but when taking digital photos in RAW mode, one needs some
> hefty memory space, which seems to be where the SDHC cards are aimed. They
> seem to start at 4GB, and go on up.

They are primarily being positioned as the next stage in digital video
media.  I just purchased a Canon HF100*, which is a 1080 HD camcorder
that records directly to SDHC at up to 17Mbits/S (about 1 hour at
highest resolution, best quality on an 8GB SDHC card).  SDHC has
further specifications called "classes" which, IIRC, indicate the
Mbytes/S.  This camera, for instance, requires a class 4 SDHC card for
the highest recording bandwidth, but can use class 2 (slower) for all
others.  Big advantages over over media: no mechanical noise
associated with recording to DV tape or DVD disk, lower power read and
write, works directly in common (cheap) flash memory readers.

They are dropping in cost, though a DV tape or miniDVD is still
cheaper.  $25 for a cheap 8GB class 6 SDHC card vs $2 for a cheap
miniDV tape (11GB), $5 for a dual layer mini-dvd (2.8GB).

> I assume this means they use a different file system than the SD cards,
> something more like NTFS, or one of the *nix types maybe, that can handle
> the larger volumes.

No, they are still primarily FAT32 - it has the greatest compatibility
across computing platforms, and is simple and royalty free.  The SDHC
spec, I've heard, limits the cards to 32GB or less, but the interface
and the filesystem could allow for higher capacities, and my suspicion
is that it won't be too long before they officially accept much larger
capacities, though I'm sure manufacturers will start producing such
cards before then.

-Adam

* Yes, it's a very nice camcorder, which I wouldn't have purchased
except that Embedded Systems does, in fact, give out the $500 amazon
gift certificates for survey participation that they say they do.
Given the number of surveys I've filled out over the years, though, I
doubt that I'm made much more than $5-10 per hour.  Still an
unexpected and very pleasant surprise.

--
EARTH DAY 2008
Tuesday April 22
Save Money * Save Oil * Save Lives * Save the Planet
http://www.driveslowly.org
<bc7a59a0807170733m845d7abt1aff0902c7d473e2@mail.gmail.com> 7bit

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